Method of repairing reheating furnace bottoms



Patented Aug. I4, 19

UNITED VMETHOD"oliREP-Amina' REHEATING FURNAcE ocrToMsV John H. Hyche, Fairfield, Ala. Application December 29, 195o, serim'N'e.-V .203,396r

3 Claims. l

This invention relates to methods of making and repairing bottoms in furnaces for reheating steel blooms, billets, slabs, bars and the like.

An object of the invention is to provide improved methods for making or repairing furnace bottoms in which the material forming either a whole bottom or a patch in an existing bottom is fused in place, but at temperatures sufficiently low as not to injure the furnace walls and roof.

A further object of the invention is to provide improved methods for making or repairing furnace bottoms in which the region where a section of bottom is to be made is filled with ferrous scrap material which melts at 2450 to 2500 F., next the furnace is heated sufliciently to fuse this material without reaching a temperature injurious to the furnace and then is cooled to resolidify it, and finally the resulting bottom section is covered with a layer of pulverized refractory, such as chrome ore.

A further object of the invention is to provide improved methods which comprise the foregoing steps and optionally can include the laying of a dam around the region to confine material While molten to the region where it is needed.

In accomplishing these and other objects of the invention, I have provided improved details of structure, a preferred form of which is shown in the accompanying drawing, in which:

Figure 1 is a top plan view of a portion of the bottom of a reheating furnace which has a patch laid in accordance with the method of the present invention;

Figure 2 is a vertical sectional view taken substantially on line II-II of Figure l.

Figure 3 is a view similar to Figure 2, but showing the materials which form the patch laid in place before fusing.

The drawing shows a typical reheating furnace bottom, which includes layers of refractory brick IIJ and a layer of refractory plastic or cement I2. The remainder of the furnace is not shown, since it can be of any standard or desired construction. Such furnaces heat steel shapes, such as blooms, billets, slabs, bars and the like, to ternperatures around 2300 F., to enable these shapes to be hot worked. The furnace refractories can safely withstand temperatures up to about 2450 01 2500" F., but temperatures higher than this are injurious to the walls or roof.

According to the broader aspects of the present invention, the region where a patch or a bottorn is to be made is cleaned out and the resulting cavity is filled with loose ferrous material I3 (Figure 3), which can be, for example, mill scale,

scar'ngs, pig iron, cast iron scrap or high carbon steel scrap. The furnace next is heated to a temperature of around 2450 to 2500 F., which fuses this ferrous material. The furnace then is cooled to re-solidify this material, indicated at I4 (Figure 2). The temperature to which the furlnace is cooled can be its usual working temperature of around 2300 F. Finally a layer I5 of granular refractory is spread over the section of bottom thus formed. The furnace bottom now is ready for normal usage.

More specifically a preferred way of practicing the present invention is as follows:

The loose ferrous material I3 includes a bed I6 of mill scale, a layer I 1 of scarngs, a layer I8 of cast iron or high carbon steel scrap, and another layer I9 of scarfings (Figure 3), which are laid down in succession. The total quantity is sucient almost to fill the cavity after the ferrous material is fused, so that unfused it is heaped somewhat above the remainder of the bottom. A dam or ring 20 of granular refractory, such as chrome ore, can be laid around the cavity, although this step ordinarily can be omitted when the furnace bottom is level. The furnace is heated to the aforementioned temperatures to fuse the ferrous material and then cooled to re-solidify this material. Another layer 2I of mill scale is laid over this section of bottom. Finally the layer I5 of refractory is applied. When the dam 20 is used, this dam can be smoothed over to furnish the layer I5 of the nal patch.

The drawing shows the method of the present invention used for patching an existing furnace bottom, but it is apparent that the same procedure can be followed for making an entire new bottom. Therefore I intend the expression making a bottom as used hereinafter in the claims to refer generically to making either a patch or a whole bottom.

From the foregoing description it is seen that bottoms made in accordance with the present invention are fused and thus can withstand normal usage without unduly wearing. They do not necessitate heating the furnace to injurious temperatures. Actual use has demonstrated that furnaces having such bottoms have withstood heating of very large tonnages of steel without failure.

While I have shown and described only a preferred embodiment of the invention, it is apparent that modifications may arise. Therefore, I do not wish to be limited to the disclosure set forth but only by the scope of the appended claims.

I claim:

1. A method of making bottoms in reheating furnaces comprising filling the region where the bottom is to be made with ferrous material, heating the furnace to a temperature of 2450" to 2500 F., which melts said ferrous material, cooling the furnace sufliciently to re-solidify said ferrous material, and covering the re-solidified material with granular refractory. v,

2. A method of making bottoms in reheating furnaces comprising laying a bed'of mill scale over the region where the bottom is to be made, covering this bed with additional loose ferrous material, heating the furnace to a temperature of 2450" to 2500 F., which melts said ferrous mate- '4 rial, cooling the furnace sumciently to re-solidify said ferrous material, and covering the resolidied material with another layer of mill scale and a layer of granular refractory.

3. A method of making bottoms in reheating furnaces comprising surrounding the region where the bottom is to be made with a dam of granular refractory, filling this region with ferrous material, heating the furnace to a temperature of 2450" to 2500 F. which melts said ferrous material, cooling the furnace sufficiently to re-solidify said ferrous material, and smoothing o the refractory forming said dam over the re-solidied ferrous material.

JOHN H. HYCHE.

No references cited. 

